[1000mp] Re: Maybe dumb questions ?

[Rob Atkinson]

Hi Mike; thanks.

73,

rob / k5uj

On Friday, November 4, 2005, at 06:37 AM, Mike Schatzberg wrote:

> Hello Rob:
>
> To try and tune your Mark V into your amp a SWR of 1.5:1, you might 
> try two things.
>
> Firstly, if your input cable to your amp is just a short jumper, try a 
> cable of perhaps 15 to 20 feet of RG 8 type coax instead.
>
> Secondly, force the tuner to adjust while in the CW mode, and sending 
> a string of dits at perhaps 35 words per minute.  If the tuner 
> memories are full, you will want to do a memory reset first.  This is 
> a good idea particularly if you change the input cable.
>
> I have found that the tuner will reduce the indicated SWR better with 
> the above method, and reach 1:1 in my Mark V.
>
> You may see the SWR decrease with just the addition of the longer 
> cable, and no tuner will be necessary at all with the 1:1 match.
>
> If your amp has a tuned adjustable input, after you add the cable, you 
> can tune the amp input for minimum SWR as well.
>
> 73 and Happy Dxing,
>
> Mike
> WB2AJI
> ----- Original Message ----- From: "Rob Atkinson" <k5uj at sbcglobal.net>
> To: "All about Yaesu 1000mp" <1000mp at mailman.qth.net>
> Sent: Friday, November 04, 2005 6:43 AM
> Subject: Re: [1000mp] Re: Maybe dumb questions ?
>
>
>> I've driven my amp with a ts870s using its internal tuner and never 
>> had a problem.   in fact, when the rig sees a 1.5:1 vswr and folds 
>> back, the tuner takes that down to 1.2:1 so the rig is happy, puts 
>> out full power and drives the amp more.   with my mk V the built in 
>> tuner doesn't seem to want to do anything with 1.5:1 so i don't use 
>> it and because it has a 200 w. pa, it can provide plenty of drive 
>> anyway.   the mk V tuner seems to be intended to only handle higher 
>> ratios, maybe 2:1 on up.
>>
>> rob / k5uj
>>
>> On Thursday, November 3, 2005, at 10:18 AM, Scott Manthe wrote:
>>
>>> Because as you tune the amplifier, the values of impedence and 
>>> reactence the internal tuner in your rig sees are changing, 
>>> therefore changing the output of the rig. I call this "tuner 
>>> wander," because the tuner wanders around trying to find a match and 
>>> I don't think it's good.
>>>
>>> Now, if you tune-up fast and don't change values, it's probably much 
>>> better than running the rig into a huge mismatch. But for me, I 
>>> prefer to turn the tuner off. Since my LK-500ZC has a very good 
>>> tuned input, it's not an issue.
>>>
>>> 73,
>>> Scott, N9AA
>>>
>>> John Becker wrote:
>>>
>>>>> It's never a good idea to use an internal tuner with an amp.
>>>>>
>>>> Why is this necessarily a bad idea? The input of my homebrew 4-1000 
>>>> amp apparently isn't close enough to 50 ohms on 15 meters for the 
>>>> Mk. V without the tuner, but I've been driving it successfully by 
>>>> using the tuner.
>>>>
>>>> 73,
>>>>
>>>> John, K9MM
>>>>
>>>
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>>
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